Answers : (1)

Unfortunately there is no topic that is not linked to other topics. Which means a particular Question can be a combination of any number of topics.

So no topic can be safely left.

At the max,

In Maths, topics like 3D, Permutation&Combination, Probability, Matrices & Determinants can have some individuality (But Questions from these topics will be based on other topics). So you cannot afford to leave out other topics.

In Physics, Modern Physics, Thermodynamics & Heat, Sound, Light and Waves and Oscillations can have individuality. But all of these topics are very important.